Designing for Transportation Management and Operations: A Primer

3. Design Considerations for Specific Types of Operations Strategies

Proper design of operational elements and inclusion of M&O considerations in typical infrastructure projects provide an opportunity to maximize the efficiency of a transportation system. Future deployments can be jeopardized when operations considerations and provisions are not included in projects. This chapter provides an overview of M&O strategies and considerations for incorporating operations into the design of transportation projects. It is intended to help designers understand what design issues may be associated with specific operations strategies and how to include these strategies on typical transportation infrastructure projects. It should be noted that many of these strategies can also be deployed on a standalone basis where appropriate. Many strategies and design considerations described in this chapter are repeated in various sections due to the overlap and interdependence of these strategies. For example, freeway management and arterial management are essentially broader categories that include elements of subsequent sections of the chapter, such as managed lanes, active traffic management, and maintenance. The decision of which operations strategies to consider during the design of projects may often be driven by overarching operations objectives and a concept or plan for managing and operating the transportation system.

3.1 Freeway Management

Freeway operations and traffic management involve managing travel and controlling traffic. The application of appropriate policies, strategies, and actions can mitigate any potential impacts resulting from the intensity, timing, and location of travel and can enhance mobility on highway and freeway facilities. Freeway management systems can improve the efficiency of available capacity, improve safety, and support TIM activities. These systems can also be used to mitigate existing features in the cases of curve warning systems or runaway truck ramps.

The FHWA's Freeway Management and Operations
Handbook states: "Freeway traffic management
and operations is the implementation of policies,
strategies and technologies to improve freeway
performance. The over-riding objectives of
freeway management programs are to minimize
congestion (and its side effects), improve
safety, enhance overall mobility, and provide
support to other agencies during emergencies."
By following the strategies and design considerations
described in this chapter, designers can support
the strategies described in the Handbook.34

During the design phase for freeways, many operational strategies need to be accommodated. Design for non-recurring congestion caused by weather events, accidents, construction, emergency repairs, and other events must be integral to the physical design of the facility.

As technology has become more integrated with the transportation system, the opportunity to utilize ITS and other means to manage freeways has become more prevalent. Various devices and systems placed on freeways, including CCTV, dynamic message signs (DMS), and ramp meters, have changed the way freeways are operated, but have not adequately changed the way they are designed. ITS and other technologies are too often treated as an afterthought in the design process; designers tend to "fit them in" rather than design optimal locations for them.

The challenge now is not just to include technology
in a project, but make it a seamlessly integrated
portion of the design, similar to the design of stormwater
management, utilities, or guardrail. When ITS is included
on a new or reconstructed facility, efforts should
be made to integrate the devices and communications
into the overall design of the facility in order to
ensure optimal placement of the devices. Since ITS
is used to monitor and manage the freeway, the locations
of devices are crucial. For example, a DMS displaying
a message to travelers about the congestion they are
currently sitting in is not located in a place where
it can have maximum effectiveness. Rather than locating
the sign where there is available right-of-way, the
sign should be located to improve the operation of
the facility. Considerations such as sun glare, guide
sign spacing, spacing from the next interchange, and
visibility due to horizontal or vertical curvature
are just a few of the design considerations for placement
of a DMS, as well as for other freeway management
strategies. To embrace designing for operations, designers
must explore these considerations within the framework
of the overall design of the facility.

Table 1 identifies elements to consider during design that can impact freeway operations. It also shows potential opportunities for designers to structure their roadway design (or redesign) to allow for more cost-effective implementation of freeway management strategies in the future. Some of these design considerations would apply to multiple strategies.

An additional resource to supplement the design considerations for ramp meters listed in the table below is the FHWA Ramp Management and Control Handbook.35 This reference contains a section focused on design considerations for ramp metering based on a variety of ramp metering design manuals and guides from across the United States.

Provide travel time information
for all available modes of transportation,
including light rail, bus, and subway.

Build areas to allow portable changeable
message signs (CMS) to be deployed
due to DMS outages and repairs.

Managing Weather Events

Consider anti-icing devices for
bridges.

Consider locations for full road
weather information system sites or
individual components for specific
conditions (e.g., wind or fog).

Consider providing storage sites
for maintenance.

ITS and Communications Technology

Install conduit for fiber optic
networks and expansion of communications
devices for ITS and other technology
along the freeway.

Provide adequate points of access
for ITS devices as well as other agencies'
needs, such as automated enforcement.

Figure 15. Road Weather Information Systems (RWIS) may be considered to support freeway management during weather events.(Source: Tennessee Department of Transportation)

3.2 Arterial Management

Arterial management involves implementing practices and operations strategies that promote the safe and efficient use of arterial roadway capacity to manage congestion. It also promotes the idea of treating the transportation system as a network that serves transit, bicycles, and pedestrians in addition to motorists. Improved modeling capabilities have improved understanding of how the transportation system is a connected network: what happens in one location affects another. Design of freeway, arterial, and bridge projects must consider impacts on the operations of the local transportation network. Agencies must work together regardless of jurisdiction to ensure the proper strategies are put in place to mitigate the impacts on the surrounding network.

Caltrans applies ramp metering as a crucial operational strategy for managing traffic and has developed two documents to guide project developers and designers in the planning and design of ramp meters. The Caltrans Ramp Metering Design Manual defines the "traffic operational policies, design standards and practices for ramp metering installations at new or existing entrance ramps," whereas the second document, the Ramp Metering Development Plan, establishes a list of each ramp meter currently in operation or planned over the next 10 years throughout California. The development plan is framed as a tool to facilitate coordination between functional units in Caltrans and with external partners in the planning and programming of ramp meters. Caltrans has also incorporated ramp metering into its statewide training courses to help integrate ramp metering throughout the project planning, design, and construction process. The ramp metering design manual contains information on storage length, HOV preferential lane, modifications to existing HOV preferential lanes, enforcement areas, and maintenance pullouts.

The ramp metering design manual instructs project development teams to consult the District Operations Branch before beginning any ramp meter design thus encouraging cross-functional collaboration. The manual also indicates that any freeway segment identified within the development plan should include provisions for ramp meters.

Figure 16. Gates to manage highways during weather events or emergencies may be considered during design.(Source: Tennessee Department of Transportation)

3.2.1 Cooperation of Municipalities

Because arterials often fall under the jurisdiction of different agencies, managing arterials properly requires cooperation and collaboration with neighboring communities. A project under one jurisdiction should achieve a level of operation similar to the rest of the corridor. In order to accomplish this, agencies may need to form agreements. For example, to move traffic through the signals on a multi-jurisdictional corridor in order to maintain traffic flow, a designer may need to connect to another agency's network to share intersection data, share information on preemption for transit and emergency vehicles, or consider special event timing plans.

These agreements can be formal concepts of operations or memoranda of understanding, or they can be informal "hand-shake" agreements that have been institutionalized through years of effort. Designers must educate themselves on the content of these documents or other collaborative arrangements to understand how a project may impact the arterial as a whole. These agreements help agencies share a common language regarding operational goals, performance measures, and strategies to manage the arterial.

Figure 17. Example of a facility design that did not account for pedestrians or bicycles.(Source: SAIC)

Intersection Control Evaluation (ICE) is a process by which the most appropriate traffic control is selected through a holistic decisionmaking framework. Significant intersections are targeted, and impacted agencies provide feedback on which traffic control strategies to deploy (e.g., traffic signal vs. roundabout). This process helps support context sensitive solutions such as road diets and complete streets. Minnesota DOT practices ICE and has an Intersection Control Evaluation Guidelines for Implementation document. Caltrans is considering adopting the practice as well.

3.2.2 Managing Access for All Modes

Managing access is a primary strategy for improving operations on an arterial. Many agencies have guidelines on design elements such as driveway spacing, corner clearance from major intersections or interchanges, and the optimum location of signals and roundabouts. While these provide foundational knowledge to apply to arterials, designers cannot expect to follow the guidelines exactly, as adjustments are often necessary.

Designers should check for operational impacts due to deviations from these guidelines. For example, when implementing context-sensitive solutions such as road diets and adding bicycle facilities, the operational impacts of the following should be considered:

Intersection traffic control (e.g., pre-timed, actuated coordinated, closed loop, adaptive control, roundabouts) – Selection requires a detailed analysis to balance cost, travel time, and delay for all modes as well as other defined operational parameters.

Median treatments (e.g., pedestrian refuge, center turn lanes, raised medians) – These treatments can impact the overall safety for all users of the facility, access to adjoining property, and efficiency for all modes.

Multimodal transportation facilities – this including bus stops or turnouts and bicycle lanes.

Figure 18. The photo highlights the importance of considering safe, efficient pedestrian access to bus stops as part of a complete arterial management strategy. (Source: SAIC)

Designers planning physical changes to an arterial roadway will need expertise in traffic operations in order to evaluate these changes because a simple report about level of service will not adequately address operational issues. Proper design and management of intersection traffic signalization is essential to optimizing the operation of arterial roadways. Designers must consider the overall corridor and roadway network signalization concept when designing a project for individual intersections. Questions about managing queues, operating speeds, safety modeling, and impacts due to growth in traffic and increases in pedestrian and bicycle modes need to be addressed. Designers should provide for in-pavement loops or other traffic monitoring devices to allow for operational assessments, including signal timing and progression.

Table 3 identifies elements to consider during design that can impact arterial operations. It also shows potential opportunities for designers to structure their roadway design (or redesign) to allow for more cost-effective implementation of arterial management strategies in the future. Some of these design considerations would apply to multiple strategies.

Designers can facilitate regional operational
practices and procedures by providing technical
information to support multi-agency agreements.
For example, designers can provide intersection
dimensions for a system-wide change of clearance
intervals of signalized intersections.

For regional traffic signal systems, designers
must consider how communications and maintenance
will be managed since multiple agencies may
be responsible for a single system. Agreements
between agencies should be developed during
the design stage to address these issues.

Context Sensitive Solutions (e.g., complete
streets)

When constructing or upgrading sidewalks,
eliminate other barriers to pedestrian access
by adding countdown pedestrian signals, pedestrian
ramps, and associated hardware and conduit
for these treatments.

Contact the appropriate department or agency
to update pedestrian timing at signals.

Facilitate transit operations by implementing
strategies such as bus turnouts, preemption
for buses, and directional signing of transit
facilities.

3.3 Active Traffic Management

Active traffic management (ATM) and managed lanes (see Section 3.4) are becoming increasingly popular in the United States as facility operators seek innovative solutions that can improve throughput and safety on congested facilities largely within the footprint of existing highways, thus requiring little or no roadway widening.

Figure 19. ATM lane control signage on a highway in Washington is placed in a high-visibility location to optimize operations.(Source: Washington State DOT)

ATM is the dynamic management of recurrent and non-recurrent congestion based on current and forecasted traffic conditions. ATM focuses on maximizing trip reliability through approaches that seek to increase throughput and safety through the use of integrated systems and new technology. ATM includes the automatic and dynamic deployment of M&O strategies to optimize performance quickly and avoid the delay that occurs with manual deployment.

Some ATM strategies, such as ramp metering and variable speed limits, have been successfully implemented within many parts of the United States. Most other ATM strategies are relatively new concepts in the United States; however, they have been successfully implemented in many parts of Europe.

During original roadway and ITS design,
provide adequate conduit in the median barrier
or shoulder to accommodate future DSL signage.

Consider line-of-sight impacts in placement
of DSL signs.

Consider how DSL signs will compete with
other signs.

Speed Harmonization

If gantries are used, locate periodic overhead
signage that takes into account how sight
distance is affected by vertical/horizontal
alignment, the ease/expense of retrofitting
with sign foundations, and required spacing
for messaging.

Consider catwalks or other means of maintaining
equipment while limiting lane closures.

Dynamic Lane Use Control

During placement, consider special geometric
characteristics and driver decision points.

Consider line-of-sight impacts in placement
of lane control signs.

Ensure that lane control symbol options
(text, symbols) comply with the Manual on
Uniform Traffic Control Devices (MUTCD).

Consider catwalks or other means of maintaining
equipment while limiting lane closures.

Dynamic Shoulder Lanes (Hard Shoulder Running)

Provide emergency pull-off areas where right-of-way
allows.

Design exceptions for geometric standards,
including lane width, vertical and lateral
clearance, and stopping sight distance may
be required.

Optimally, include an expert system to deploy
the strategy based on prevailing roadway conditions
without requiring operator intervention.

Dynamic merge control requires overhead
electronic signage.

3.4 Managed Lanes

Impacts of not considering operations during design. It is common for ITS specifications to provide recommended spacing of certain devices, and designers have effectively applied such
spacing on traditional highway projects. Managed Lane and ATM applications require much more precise locations to fit project-specific needs. For example, generic placement of variable message signage could lead to providing real-time traffic and toll rate information beyond the point on the facility where a driver can use the information to make a route choice decision. Furthermore, the proliferation of information available through ATM applications can lead to confusion and apathy on the part of the driver. The information must be delivered in a very specific sequence and location in order to be of most use to the driver and operating agency.

Managed lanes are highway facilities or a set of
lanes where operational strategies are proactively
implemented and managed in response to changing conditions.
Managed lane projects take lane management strategies
that have been used extensively for decades-such as
HOV lanes, bus-only lanes, truck lane restrictions,
and express lanes-and incorporate the concept of active
management. These strategies can be implemented utilizing
concurrent flow lanes (adjacent to general purpose
lanes), reversible flow lanes, contra flow lanes,
or existing shoulders. Colorado DOT took enforcement
needs into consideration when designing their high-occupancy
toll (HOT) lanes by adding a widened shoulder (see
Figure 21).

Caltrans issued guidance in 2011 titled "Traffic Operations Policy Directive 11-02 – Managed Lane Design," which institutionalizes the practice of designing for operations. The directive states that it "shall be applied during the planning and development of freeway managed lane projects, including conversion of existing managed lanes to incorporate tolling or utilize continuous access. It shall be considered during the planning and development of all other freeway improvement projects (e.g., pavement rehabilitation project) and during the course of traffic investigations that are addressing operational and safety performance deficiencies."36

Table 5 identifies elements to consider during design that can impact managed lane operations. It also shows potential opportunities for designers to structure their roadway design (or redesign) to allow for more cost-effective implementation of managed lane strategies in the future. Some of these design considerations would apply to multiple strategies.

In order to optimize transit use of a managed
lane facility, consider major bus routes when
locating weave zones to enter and exit the
lanes.

Access/egress zones for buffer separated
facilities must be carefully located, with
consideration given to traffic patterns from
intersecting facilities. Operations and safety
are optimized by locating access and egress
on tangent alignments.

Express Toll Lanes

Ensure that traveler information and toll
rate signage is provided in advance of the
driver’s decision point regarding whether
to use the managed lane(s).

Barrier separation is typically preferred
but often impractical due to expense and right-of-way
needs. Buffer separation of two to four feet
provides separation from the general purpose
lanes, which can have slower travel speeds
than the express toll lanes.

Managed lanes require weave zones for access
and periodic widened shoulders for enforcement.
While there is commonly not enough right-of-way
to widen the entire length of a future managed
lane, there might be certain locations along
the corridor that can be preserved for such
use. During the original design, avoid unnecessarily
precluding these opportunities.

Truck-Only Toll Lanes

Initial pavement design can take into account
heavier design loads when a truck-only toll
lane is anticipated in the future

Reversible Lanes

In conversion of reversible lanes from
HOV to HOT operations, roadway design may
require provision of adequate width at certain
points in the corridor for tolling gantries
and enforcement.

Enable emergency personnel to respond to
incidents on a facility with limited access

Address the need for monitoring and proper
deployment/closures during directional changes.

Drainage structures and grates should be
initially designed to align with wheel paths;
adjustments after-the-fact can require major
reconstruction.

May require slight adjustments in vertical
and horizontal clearance. These can be very
costly, if not prohibitive, to retrofit.

3.5 Transit

During the design of a transportation facility, the transit rider must be considered just like the motorist. Transit provides the ability to increase the throughput of a facility, thereby improving overall facility operations. There are opportunities on both freeway and arterial facilities to incorporate transit operations considerations into design. One high profile application for transit on freeways is bus-on-shoulder (BOS) or bus-only shoulder. There are documented examples of BOS in California, Florida, Georgia, Maryland, Minnesota, New Jersey, Virginia, Washington, and Delaware. Minnesota is a leader in BOS operations, with more BOS lane miles than the rest of the country combined.

Minnesota DOT has developed guidelines for geometric design and signing for bus-only shoulder operations.38 Geometric standards regarding lane widths, vertical clearance, stopping sight distance, and lateral clearance/clear zone must be considered and may not always be full design standards for retrofit applications.39 Figure 22 shows the use of minimum 10-foot shoulders.

A BOS program ensures that buses can achieve significant travel time savings by not having to enter the weave through general purpose traffic to enter or exit an interior managed lane. Some of the routes in Minneapolis experienced a 9 percent increase in ridership. A successful BOS implementation requires highway designers and transit operators to work together to implement a solution that considers ramp operations, merging, and weaving. BOS can be implemented in conjunction with managed lane strategies or ramp metering.

Another important transit operations strategy is bus rapid transit (BRT). BRT is an advanced bus system that relies on several techniques to provide faster travel times, greater reliability, and increased customer convenience over ordinary bus service. BRT offers the flexibility of buses and the efficiency of rail by operating on bus lanes or other transitways and applying advanced technologies or infrastructure such as transit signal priority and automatic vehicle location systems.41

Florida DOT District 4 (Ft. Lauderdale) is studying transit queue jumps for use on heavily congested arterials, including the impacts of queue jumps on intersection and approaching roadway geometry. They will evaluate the traffic control devices and transit operator protocols associated with queue jumper operations and will assess their impact on other arterial traffic. They will develop a design "template" that can be utilized to identify intersections at which queue jumping should be provided and to guide the design/placement of associated traffic control devices and the design of any needed roadway modifications. The template will be systematically used in future resurfacing and other projects.

Transit operators understand best which strategies work best for certain corridors. Transit agencies should be engaged in design to help select the most appropriate features that allow for the maximum efficiency of the facility. Rather than retrofitting an existing freeway or arterial with these types of strategies on a case-by-case basis, they should be considered as part of an overall corridor management strategy and mainstreamed into the design process.

Table 6 identifies elements to consider during design that can impact transit operations. It also shows potential opportunities for designers to structure their roadway design (or redesign) to allow for more cost-effective implementation of transit strategies in the future. Some of these design considerations apply to multiple strategies.

In order to optimize transit use of a managed
lane facility, consider major bus routes when
locating weave zones to enter and exit the
lanes.

Bus Rapid Transit (BRT)

Consider additional right-of-way to accommodate
in-line stations or direct access ramps to
optimize operations for stations that are
adjacent to the facility. Design should allow
for acceleration/deceleration lanes for
buses needing to re-enter or exit lanes that
may also operate as HOV lanes. For future
BRT, initial roadway geometry should be designed
to allow for future in-line stations and direct
access ramps.

Ensure that traveler information and toll
rate signage is provided in advance of the
driver's decision point regarding whether
to use the managed lane(s).

Pedestrian access from park-and-ride lots
and circulation is critical for peak operational
efficiencies and should be integral to the
design process.

Designated Transit Lanes

Initial pavement design can take into account
heavier design loads when transit use is anticipated
in the future.

Provide Access to Park-and-Ride Lots

Bus access must be designed to minimize
circulation and dwell time by providing direct
access (dedicated ramps, priority signalization)
from the adjacent highway facility. For park-and-ride
lots that also function as transfer stations
(bus to express bus, bus to rail), the parking
side of the lot should also provide priority
to buses.

Roadway DMS Used for Transit Information and
Comparative Travel Times for Alternate Modes

DMS must be placed in advance of the point
on the facility where a driver can use the
information to make a mode choice decision
and safely weave to access a park-and-ride
lot.

For future transit corridors, roadway and
structure design will need to provide for
overhead signage at those locations.

Park-and-Ride Space Finders

Similar to DMS (above), these systems must
be located strategically so that real-time
information is transmitted to drivers at
a point where it can effectively aid in decision-making
regarding transit and carpool use.

Bus-on-Shoulder

Because most bus-only shoulders are retrofit,
consideration of lane delineation and signage
conventions should occur in the design phase
to ensure regional consistency. Bus-only shoulders are for professional drivers only, so
training can be geared to operating buses
within these conventions.

Provide full-depth shoulders during normal
paving operations to avoid tearing out the
shoulder and sub-base for future lanes.

Drainage structures and grates should be
initially designed to align with wheel paths;
adjustments after-the-fact can require major
reconstruction.

Arterial Bus Lanes

Bus stop placement (near side vs. far side
of intersection) has a significant impact
on bus operations. Transit agencies need
to be involved in the design stage as bus
stop locations can depend upon the type of
service (local, express).

Transit signal priority (TSP) works in
conjunction with the bus stop locations to
optimize express bus operations. The transit
agency should have input in the design of
the facility and the TSP software programming.

Where space permits, queue jump lanes can
be used at signalized intersections in conjunction
with TSP to reduce dwell time at stops. Adding
queue jump lanes requires transit agency input
in the design process.

3.6 Work Zone Management

Managing traffic during construction is necessary to minimize traffic delays, maintain or improve motorist and worker safety, complete roadwork in a timely manner, and maintain access for businesses and residents. Work zone traffic management strategies should be identified based on project constraints, construction phasing/staging plan, type of work zone, and anticipated work zone impacts.42

Evaluate need for temporary traffic signals and integrate them into the existing system so they can be timed appropriately.

Agencies should consider performance-based maintenance of traffic requirements, such as maximum allowable delay, rather than geometric or time of day restrictions. This approach allows greater creativity and innovation by contractors, which may result in both cost savings to the agency and time savings to motorists.

A transportation management plan (TMP) is a successful
approach to identifying transportation management
strategies and describing how they will be
used to manage the work zone impacts of a
project. The FHWA publication Developing
and Implementing Transportation Management
Plans for Work Zones defines planning
and design considerations for work zone management.
Throughout the development of a TMP, designers
and operational stakeholders have the opportunity
to consider the impacts of their work zones
and to identify strategies to improve work
zone performance.43
The TMP is primarily intended for managing
traffic during a construction project. However,
some of the elements of the TMP, particularly
ITS improvements, could remain in place to
aid ongoing operations. Additionally, the
cross-functional and interagency relationships
formed during the development and use of the
TMP should be continued after the project
to promote a coordinated approach to operating
the facility.

The inclusion of work zone management and operations should be identified during needs development and preliminary engineering so that strategies can be implemented prior to the start of major construction activities if needed. In addition, the transportation facility should be designed with construction and post-construction maintenance of traffic activities in mind. Designers must consider how the facility will be constructed in a manner that provides a safe working environment and minimizes the impact on the operation of the facility. This may require consideration of construction methods and staging.

Traffic capacity and shoulder/pullout areas are often
restricted in work zones. Prompt detection
and clearance of traffic incidents in work
zones can help reduce secondary crashes and
delay. Preparing a work zone TIM plan and
using strategies that improve detection, verification,
response, and clearance of crashes, mechanical
failures, and other incidents in work zones
and on detour routes can benefit safety and
mobility. Specific strategies are identified
in FHWA's, Traffic Incident Management
in Construction and Maintenance Work Zones.44

3.7 Traffic Incident Management

Traffic incident management (TIM) practitioners become well aware of shortfalls in operational provisions when it affects their ability to respond to incidents safely and efficiently. There are several ways that designers can ensure that the needs of this end-user group are considered and included in the final design of a project. The National Unified Goal (NUG) for TIM is a foundational element of a well-developed TIM Program and provides a valuable opportunity to link program decisions to physical design. Table 7 identifies elements to consider during design that can address various NUG strategies.45

Provide static signs directing responders
to investigation sites, including1/10 mile
markings and a system to identify locations
on ramps within complex interchanges.

CCTV should be designed and constructed
in high-crash locations to improve detection
and verification time.

Strategy 17 – Prompt,
Reliable Traveler Information Systems.
Partners should encourage development
of more prompt and reliable traveler information
systems that will enable drivers to make
travel decisions.

Figure 23. One of the design considerations for TIM is shoulder width for accommodating response vehicles.(Source: Florida Department of Transportation)

During the design phase, the project team should seek input on roadside safety from emergency responders or a TIM team at important milestones, such as the transition from preliminary engineering to final design. Input from responders on roadside features such as noise walls, median barriers, and ITS device locations should be considered a priority in the design process. If a local TIM team does not exist where the project will be located, the project team should establish one with the goal of creating a framework that will ensure continued TIM team existence after the project is complete. During construction, the TIM team should be engaged to ensure that both constructability and emergency response risks are balanced.

It is important to develop a good rapport with emergency responders during a construction project. An effective way to make the best use of their time and to gain valuable insights into their operational needs is to conduct a table-top exercise that includes the proposed design. After the design plans have reached a level that makes it clear what will change from the existing situation, the design team should gather the local TIM team members or establish the TIM team and conduct a table-top exercise to "test" the design for operations. In addition to agency design personnel, the team should include maintenance staff and emergency responders. It is suggested that at least three scenarios be included during this session to generate discussion:

A crash and subsequent release of hazardous materials.

A full directional blockage during construction when access is reduced.

A full directional blockage for the final condition.

In addition to documenting the needs of emergency responders in each of these scenarios, there should also be discussion about how the response to these scenarios differs if construction workers are present at the incident site. The response to less severe events should also be covered.

Permanent Median Crossovers

At approaches to major bridges or freeway segments where there are long distances between exits, designers should consider converting construction detour crossovers to permanent cross over facilities to accommodate detours for incident management. The crossover should have proper treatments, such as delineators, to protect against wrong-way use.

3.8 Security

Transportation agencies need to deploy appropriate risk reduction methods to minimize or eliminate identified vulnerabilities in their system, and designers need to consider if countermeasures are appropriate for their particular project. NCHRP Report 525 – Surface Transportation Security discusses many of the tools and countermeasures that should be considered in the design phase as a means to improve the security of critical infrastructure and facilities, information systems, and other areas.47 Physical security countermeasures that should be considered by a designer may include signs; emergency telephones, duress alarms, and assistance stations; key controls and locks; protective barriers; protective lighting; alarm and intrusion detection systems; electronic access control systems; and surveillance systems and monitoring.

Agencies must conduct threat and hazard analyses for use in prioritizing the most important roads and infrastructure. Controlling access to critical components, providing standoff from critical components, eliminating single point of failure construction, and ensuring that surveillance systems are tied directly into response units are the best strategies to deter or prevent terrorist or criminal acts. Many of these strategies are very costly and must be considered in the scoping phase. Even though making these decisions is beyond the authority of the individual designer, there are related elements that can be considered in the design phase.

Designers should contact internal and stakeholder security and emergency management officials to develop security and emergency management requirements. This coordination can prevent issues such as designing and building a structure for standard loads then retrospectively learning that it is a critical primary route that must be designed for moving heavy equipment into an area during an emergency. Security and emergency management planning and designing takes a community of people drawn from law enforcement/security, fire and emergency medical services, emergency management, occupational safety, and highway/transportation organizations.

Table 8 identifies elements to consider during design that can impact infrastructure security. Transportation agencies must examine the threats against infrastructure and identify the most useful means to reduce the vulnerabilities associated with those threats to acceptable levels. Often less costly but more effective solutions are available that the agency can select to meet security requirements. In making these choices, designers can benefit from an analysis that compares one countermeasure against another based on protection provided, cost, and effort required.

3.9 Freight Operations

Freight operations are an important consideration with respect to improving mobility and productivity. Improved operation can benefit the freight industry through:

Immediate cost reductions to carriers and shippers, including gains to shippers from reduced transit times and increased reliability, resulting in decreased cost of raw materials and finished goods.

Reorganization-effect gains from improvements in logistics. The quantity of firms' outputs changes, but quality of output does not.

Gains from additional reorganization effects such as improved products or new products.49

Additionally, improving freight operations enhances the safety and efficiency of the transportation system for all users by lessening the impact of freight movements on the general public and vice versa. Virginia DOT has been focused on improvements geared toward truck traffic along Interstate 81 (its most heavily traveled truck route) for years. Improvements include interchange redesign, truck climbing lanes, ITS improvements, and ramp extensions. During design, however, consideration of freight must extend beyond the geometric considerations associated with commercial vehicles to include operational elements that support enforcement and hours-of-service requirements, as well as elements to improve safety and overall efficiency.

The table below illustrates specific actions that designers can take to enhance freight operations. In some cases, where significant infrastructure improvements are involved, strategies must be initially considered in the scoping/planning phase. However, designers can optimize the effectiveness of these strategies through use of the specific design considerations.

Include slow moving vehicle lanes (upgrade/downgrade).
Designers should consider truck acceleration/deceleration
and other characteristics in locating termini
of these lanes.

3.10 Maintenance

Maintenance of a roadway can have a major effect
on operations. Maintenance personnel have a variety
of issues to deal with; from mowing operations in
the summer, to snow plowing operations in the winter,
to maintenance of roadside devices, they are constantly
working to keep roadway networks operating. Taking
into consideration certain aspects of the design of
the roadway and devices can reduce the impacts of
maintenance operations. For example, inadequate shoulder
widths may require maintenance personnel to shut down
a lane to perform their duties.

Figure 26. The utilization of two types of median treatments may impact mowing activities.(Source: SAIC)

Including maintenance personnel in the design process can help designers identify many maintenance issues that they may not be aware of. There are two ways this can be achieved. First, during the design phase, the project team should invite maintenance personnel to design meetings where they can provide input on design aspects. Input from maintenance personnel on roadside features such as noise walls, median barriers, and ITS device locations should be considered a priority in the design process.

Second, agencies should include processes or checklists in design manuals to obtain sign-off on plans from their maintenance division. Maintenance personnel should comment on issues that relate to snow plowing operations, barrier selection and placement, impact attenuator selection, signal systems and ITS infrastructure, landscaping, median crossovers/turnarounds, shoulder width, and culvert treatments, among others.

Table 10 identifies elements to consider during design that can impact maintenance operations. It also shows potential opportunities for designers to structure their roadway design (or redesign) to allow for more cost-effective implementation of maintenance strategies in the future. Some of these design considerations would apply to multiple strategies.